Energy management system for a self-sufficient university campus microgrid

Abstract

In a world where electricity demands are progressively growing along with the worsening climate crisis, it is essential to conduct research and build systems that can meet this demand in a sustainable, reliable and cost effective manner. The building sector accounts for nearly 40% of greenhouse gas emissions in the EU, this is primarily due to the dependence on fossil fuels to provide heat for spaces, heating water and for cooking. Countries have made ambitious goals to reduce these emissions, and one such way is electrification. By electrifying heating, some research suggests that all the Renewable Energy Sources (RES) planned to be deployed in the Netherlands will not be suffcient to meet the demand, even with storage technologies. There are multiple ways to address this problem, one of them is decentralising energy production such that each household or institution accounts for their own production and consumption of energy. While this is in theory a simple solution, in the higher latitudes becomes harder during the colder months to meet the increased electricity demand using only renewable sources. Thus, a combination of them must be used to combat the effects of seasonal RES production. Simultaneously, the wholesale electricity prices in the Netherlands are also projected to increase in the near future, to almost 57e/MWh. Universities being large load customers, will feel the effects of this increase in electricity prices and the need for heating electrification by 2030. This need could be due to policy implementations or personal choice. It is in the benefit of the university to increase their self-sufficiency, to decrease costs and carbon emissions. Thus, a microgrid is proposed for a university in the Netherlands. This microgrid, utilises on-site Photovoltaics (PV) generation, Fuel Cell Electric Vehicles (FCEVs) in the capacity of back up generation and a battery to store any excess energy generated by the PV system. In order to ensure the smooth integration of the components mentioned, an energy management system is designed. Furthermore, a new value proposition is made for the energy storage system where it is utilised during times of high electricity prices. For the energy management system two control strategies are proposed with different end goals; one based solely on increasing self-sufficiency, while the other is based on decreasing costs. A comparison is made to understand when each control returns the most benefits and what exactly these benefits are. Using a combination of MATLAB and Simulink each of the components mentioned above were modelled using current practices in literature. Scenarios were developed to create a basis for comparison: baseline scenario, Self-sufficiency based (SSB) scenario and Price-based (PB) scenario. The last two are collectively termed the Distributed Energy Resource (DER) scenario. The electrification of heating has a significant impact on the load prole, the largest loads occur in the winter. It was found that the highest self-sufficiency achieved was 43% utilising the SSB control, whereas with the PB control a maximum self-sufficiency of 41.3% was achieved. These percentages can mainly be attributed to the combination of large load and low PV production during the colder months of the year, indicating a clear need for studies into the impacts of heating electrification for consumers. This fraction can be increased by identifying further combinations of DERs that are sustainable, low cost and also available during the colder months of the year. Furthermore, levelised cost of electricity of the PV system accounted for only 19% of the total system levelised cost of electricity; while the zinc-bromine flow battery and and FCEVs accounted for nearly 60% of it. On average the proposed system provides energy at an average (across both controls) cost of 0.304e/kWh. The costs of the proposed system are relatively high, and the largest contributors to this are the FCEV fleet and the chosen battery.